Special lubricant systems have been developed over the years to reduce friction and prevent wear and welding between working surfaces of bearings and gear teeth when, as a result of extreme pressure, low speed, high temperatures or reduced viscosity, the film which normally completely separates moving parts becomes thin enough to permit partial metal-to-metal contact. When moving machine parts are subjected to more severe conditions of load, speed and temperature, as for example, the high tooth pressures and high rubbing velocities often encountered in hypoid and spur type gearing, base lubricating oils themselves do not have the necessary qualities to provide adequate lubrication; metal to metal contact would occur which results in scoring, galling and local seizure of the gear teeth; therefore it is necessary to employ lubricants which contain extreme pressure additives.
Extreme pressure (EP) additives are a special class of boundary lubrication additives which chemically react with the metal surface to form compounds with a lower shear strength than the metal. The resultant low shear compound thus provides the requisite lubrication. EP oils are basically inhibited oils with added extreme pressure additives.
The combination of neodecanoic acid, one of the ingredients of EP additives, with diesel fuel is discussed in U.S. Pat. No. 4,857,073, which concerns Diesel fuel additives. More particularly, it relates to a novel additive composition which can be added to the fuel of an ordinary Diesel engine and is capable of increasing the efficiency of fuel combustion within the engine, thereby boosting engine power, improving fuel economy, and reducing objectionable tailpipe emissions, especially particulates and smoke. With the '073 invention, the efficiency of combustion within an internal combustion Diesel engine is improved, and increased fuel economy of a Diesel powered vehicle is realized, by incorporating into the Diesel fuel a minor amount of a particular additive composition comprising the following components: ditertiary butyl peroxide, tall oil fatty imidazoline, neodecanoic acid, and a hydrocarbon solvent carrier about 0.5 weight percent neodecanoic acid; the particular 2/1 relative amounts of tall oil fatty imidazoline to neodecanoic acid is important to achieving Diesel fuel stability and shelf life, and detergency which assists the ditertiary butyl peroxide in its effects on exhaust particulate reduction, and exhaust and smoke reduction. The acid acts as an initiator and stabilizer for the above peroxide, and helps provide resistance to microbial attack in diesel fuel.